This invention relates to a lead introducer system and method of atrial defibrillation and, more particularly, to an introducer system for inserting a transvenous endocardial lead for the purpose of achieving atrial defibrillation.
Atrial fibrillation (AF) is one of the most common arrhythmias, and is usually associated with patients of an increased age. About ten percent of patients who are at least 65 years old present with AF. Atrial fibrillation is associated with troublesome symptoms for patients, and also has a significantly adverse influence on the cardiac function. It is also well known that there is an increased risk of embolic events following AF. Accordingly, the increased heart rate associated with AF needs to be controlled. The primary current treatments for AF are the use of anti-arrhythmic drugs, or electric cardioversion. Use of anti-arrhythmic drugs is often associated with potential proarrhythmic effects, especially in patients with already compromised ventricular function. Such a proarrhythmic effect can outweigh the potential benefit of drug administration. On the other hand, transthoracal electrical cardioversion is an extreme therapy, requiring a discharge energy in the range of 50 to 360 Joules. This treatment requires general anesthesia, and serious side effects may occur as a result. Additionally distressing is the fact that there are a substantial number of patients who may fail to being cardioverted externally.
Recently, transvenous cardioversion of atrial fibrillation and other arrhythmias has been demonstrated to be effective. The energies usually necessary to fibrillate in a case of atrial fibrillation are much lower, being in the range of about 1.0 to 5.0 Joules, depending upon a number of factors, particularly the electrode configuration. Electrode configurations that have been tried include the use of different electrodes respectively in the right atrium, right ventricle, arteria pulmonalis, vena cava superior and/or vena cava inferior. The subclavian electrode position has been found to be promising for achieving low defibrillation thresholds. Accordingly, a configuration that has been in use for atrial defibrillation involves one lead with an electrode in the subclavian vein (SCV) and another lead providing an electrode in the coronary sinus (CS). However, for most of these currently used configurations, it is necessary to puncture the vein several times for introducing two leads through the vein so as to position the electrodes for the defibrillation therapy. Alternately, the problem has been addressed by introducing one lead and placing a cutaneous electrode or needle, or temporary indifferent electrode, in the vein incision, a less satisfactory arrangement. The introduction of two leads or a lead and a second electrode is, of course, cumbersome, time-consuming, and costly. Particularly in emergency situations it is desirable to simplify the procedure as much as possible.
There thus exists a significant need in the area of atrial defibrillation, and particularly temporary atrial defibrillation, for a system enabling introduction of only a single transvenous lead to the heart for the purpose of delivering the atrial defibrillation therapy. Such a therapy is needed for patients with, e.g., paroxysmal AF, open heart surgery, or those receiving a pacemaker cardioverter-defibrillator (PCD) type device. In such applications, it is desired to minimize the effort needed to position the required electrodes properly for administering the AF therapy.